My amplified sound cube

[soundNERD]

I had some wood, little speakers, a transformer, some 3875s and a heatsink sitting around collecting dust. So, I thought, why not build something out of it. I ended up with what I call, a soundcube. What it is is two small 4" Infinity full range speakers, one on each side, in series connection for a total load of 8ohm. The speakers are driven by a LM3875TF amp.

Sound is very good, especially since I designed it with two ideas in mind, first, sound quality, and most importantly, portability. Yes, it does weigh pretty much (due to the MDF and transformers, the speakers are quite light).

Here are some pictures, what does everybody think?

Looking at the picture of the back, you see only a potentiometer , power cable, and two other wires sticking out. Wheres the power switch and input? The two wires are the input (not done, still need to add RCA jack), and the potentiometer has a switch built into it, which switches the AC to the transformer.

 

[soundNERD]

another pic

 

[MWP]

Your using a standard on/off pot switch to switch mains to the transformer??
That cant be a good idea

 

[johnnyx]

I would use a sleeved grommet or something where the mains cable goes through the metal above the heatsink. A bit of wear...and...

Good idea though. Is it small enough to replace crappy PC speakers?

 

[soundNERD]

Your using a standard on/off pot switch to switch mains to the transformer??
That cant be a good idea

Why not? The only problem is a slight humm only noticable when you put your ear next to the speakers. I can deal with that.

Also, johnnyx, yes, I will add one, need to buy one. About replacing the crappy PC speakers, its better than that. I am actually quite suprised with the sound quality. Unbelievable bass from such small speakers and good treble responce and a clean midrange, not too sharp and not too muffled. The distortion-free volume output is quite amazing to me also.

 

[soundNERD]

just reread your question, johnny, yes, it is small enough. measures 6.5" wide, 7" deep and 6.5" tall.

 

[sss]

nice sub !

 

[soundNERD]

Thanks, sss, although it really isn't a sub. It could be if I added a crossover, but I didn't want it to be.

Heres another picture of the completed rear panel with 3.5mm audio input jack.

 

[soundNERD]

hmm, not letting me post a pic. here goes again.

 

[MWP]

Why not? The only problem is a slight humm only noticable when you put your ear next to the speakers. I can deal with that.

Im thinking saftey wise.

 

[carlosfm]

Mains on a volume pot/switch.
Stay clear of headphones!
Oh, nice sub!

 

[soundNERD]

OK, someday I might change that. Its just the switch was rated 2A at 125VAC, so I thought it would be OK.

Thanks for all the positive comments also!

 

[aHobbit]

In typical radio, it is the rectified secondary that may be used in the on/off pot switch. I think you can do this if the secondary voltage is not that big - otherwise, it is really a safety issue.